Concentrated homogeneous heavy duty liquid detergent compositions are well-known in the art, and have found commercial application.
These compositions often comprise a mixture of anionic and nonionic surfactants, and generally contain electrolytes; but it has been recognized that the presence of electrolytes in concentrated liquid detergent compositions can be detrimental to the solubility of nonionic surfactants and therefore hydrotropes and/or solvents are included in the compositions.
However, conventional hydrotropes are not suitable in compositions containing less than 50% of water.
Cumene and xylene sulfonates in particular are not effective in such compositions. Other hydrotropes or compatibilizing agents, such as water-soluble solvents, can have deleterious effects: ethanol may lead to enzyme destabilization, and polyols are less desirable in presence of perfumes.
We have now found that these drawbacks can be overcome by the use of a specific class of monoesters which can function as hydrotropes in concentrated liquid detergent compositions containing less than 50% of water.
We have also found that the compositions herein, in addition to stability benefits, show improved cleaning performance.
The prior art relative to concentrated homogeneous heavy duty liquid detergent compositions is crowded and diverse. As an example U.S. Pat. No. 4,285,841 discloses builder-free concentrated homogeneous liquid compositions containing a combination of anionic synthetic surface-active compounds, nonionic surface-active compounds and fatty acids. The manufacture of the like compositions containing less than 50% water requires the utilization of substantial amounts of solvents and/or compatibilizing agents and even under those circumstances, remain of borderline stability having particularly regard to levels and types of nonionics, fatty acids, especially saturated species, and optional electrolytes such as low levels of organic builders.
The necessity to limit the level of nonionic surfactants due to increase of viscosity and phase separation problems is recognized e.g. in EP No. 0 074 134.
Monoesters of dicarboxylic acids have been used for various purposes in detergent technology, for example:
as surfactants and softening agents, FR No. 772.538; PA1 as emulsifying agents, FR No. 1.027.083; PA1 as suds suppressors, DE No. 22 54 287; PA1 as soap replacements, DE No. 11 33 061; PA1 as builders, DE No. 22 28 252. PA1 less than 50% by weight of water; PA1 from 10% to 50% by weight of a mixture of anionic and nonionic surface-active agents; PA1 at least 5% by weight, of the total composition, of a non-ionic surface-active agent; PA1 from 2% to 50% by weight of a water-insoluble monoester of a dicarboxylic acid having the formula ##STR1## wherein R.sub.1 is an alkyl or alkylaryl-group having from 8 to 20 carbon atoms, R.sub.2 is a saturated or unsaturated aliphatic moiety having from 1 to 8 carbon atoms or a saturated or unsaturated cyclic moiety with the proviso that the sum of the carbon atoms in R.sub.1 +R.sub.2 is at least 12.
The art-utilization of the dicarboxylic monoesters of the above references is different from, and not suggestive of the technology herein.
It is an object of the present invention to provide stable, homogeneous concentrated liquid detergent compositions, containing high levels of active ingredients, inclusive of nonionic surfactants and electrolytes.
It is a further object of the present invention to provide a detergent composition with outstanding cleaning performance.